1. Field of the Invention
The present invention relates to a semiconductor device comprising a semiconductor wafer having a plurality of IC chip regions and a method of burning in the same.
2. Description of the Related Art
There are two purposes of burning in a semiconductor integrated circuit. The first purpose is to positively find a latent defect (e.g., a defect in an oxide film) caused in a wafer process so that only a perfect product can be selected in the subsequent screening process. In the first purpose, a semiconductor integrated circuit is burned in by applying a great electrical stress, i.e., by applying a high voltage, under a high ambient temperature. The second purpose is to positively find a latent defect (e.g., a crack in sealing resin) caused in an assembly process so that only a perfect product can be selected in the subsequent screening process. In the second purpose, a semiconductor integrated circuit is not necessarily burned in by applying an electrical stress and it is subjected to an environmental stress such as a high temperature or a high humidity, for checking the reliability of the assembled device.
Semiconductor integrated circuits have been conventionally burned in with each individual IC chip finished as a semiconductor device and, in other words, with each individual IC chip packaged. For this reason, a burn-in equipment is enlarged and complicated, and an investment for the burn-in equipment is increased and a cost of ensuring a place required for storing the burn-in equipment is heightened, which greatly increases the manufacturing costs of a semiconductor integrated circuit device. Since the burn-in operation is carried out with IC chips packaged, even a semiconductor integrated circuit such as a memory having a redundancy circuit suffers from the problem wherein latent defects cannot be eliminated and the yield of IC chips is difficult to be improved.